Method for the removal of carbonic oxide from gases



Jan. 4, 1944. R BRANDT METHOD FOR THE REMOVAL 0F CARBONIC OXIDE FROMGASES Filed July 25 1940 Patented Jan. 4, 1944 METHOD FOR THE REMOVAL FCARBONIO OXIDE FROM GASES Richard Brandt, Berlin, Germany; vested in theAlien `Property Custodian Application July 25, 1940, Serial No. 347,565

In Germany May 4, 1938 3 Claims.

This invention relates to a method or the removal of carbonio oxide fromgases or mixtures of gases containing sulfur compounds by a contactlprocess with steam catalysis. The invention is an improvement in ormodification of the process of my copending patent application SerialNumber 202,130, filed April 14, 1938, how Patent No. 2,229,166.

In carrying into effect the method forming the subject of said priorapplication it has been found that in order to obtain a certain andextensive conversion of the carbonio oxide into carbonic acid by meansof steam particular stress must be placed on as uniform a loading aspossible of. the converter plant. In most cases the installation for theperformance of the method will be directly connected to a gas work orcoke plant as in this way costly intermediate receptacles for storingthe initial gases are avoided. In carrying out the operation in this waya certain difllculty exists in maintaining constant the saturation withsteam and obtaining a very extensive and certain conversion of thecarbonio oxide on catalysis, as varying delivery of the initial gases tobe treated, both as to the quantity and the composition, must be takeninto account.

The invention provides a method of avoiding` these diliiculties bycompensating the variations of the unpuried initial gases stillcontaining sulphur which are caused in particular by the furnace houseoperation. According to the invention this result is attained by addingto the initial gases a corresponding portion of the stream varying inquantity of already converted gases and thereby bringing their totalquantity to a constant amount. If for example the maximum delivery offurnace gases -per hour is 600 cubic metres and if the amount beingdelivered falls below this maximum amount at certain times for examplein discharging and recharging chambers in the furnace house or in theknown wet operation by gasification of coke in theretorts with steam,then by means of this returned partial flow the quantity required tomake up the amount to the maximum delivery of 600 cubic metres issupplied so that a constant loading of the conversion plant and aconstant steam saturation of the gases to be converted is attained.

In the application of the new method a particular effect is alsoobtained by balancing also the varying carbonio oxide content in theinitial gases. This is based upon the fact that during the time that thegas development is particularly vigorous, as for example after a freshcharging of the furnace chambers, the CO content of the initial gases isat a minimum. In the above mentioned example the CO content of theinitial gas amounts to 11.9 percent in case of the said maximum deliveryof 600 cubic metres per hour. During this maximum supply of furnace gasthere is little or no addition `of converted gas. Consequently, the COcontent of the gas passing through the conversion is the same as that ofthe initial gas. During the time of minimum supply of lfurnace gas, asfor example at the end of a degasification period, the CO content isgenerally at a maximum and in the above mentioned example is about 14.4percent. During this period, an increased'addition of CO-poor convertedgas takes place. If the quantity of initial gas amounts to 500 cubicmetres, as stated above, cubic metres per hour of converted gascontaining 1 percent CO only are supplied to the initial gas (preferablywith the aid of an automatic governor controlling the circulation). As aresult, the CO content is reduced, i. e., in the case of the presentexample, from 14.4 percent by volume to about 12 percent. The process ofthe present invention makes it possible to realize av substantialbalancing of CO fluctuations in the initial gas to be converted.

`In comparison with prior known processes for the removal of carbonmonoxide, wherein there is no partial return of converted gas andwherein, consequently, the gas to be converted has a fluctuating COcontent so that, with a constant supply of steam, the treatment at timesis carried is carried out with an excess of steam, the process of thepresent invention presents the advantage that the CO conversion takesplace with an appreciably smaller quantity of contact material and witha smaller quantity of steam. In addition, with a uniform loading of thecontact and with a uniform steam content in the gases, water gas balanceis realized more rapidly and more completely.

It has been found to be advantageous in carrying out the process of theinvention to precede the return of the circulating gas to the initialgases by a washing out from the circulating gases of the carbon dioxideproduced during conversion.

In order to attain the desired favourable actions the circulating gasneed not be admixed with the pre-cleaned furnace gases in the usualmanner. The admixture in fact can be effected on the low pressure sideof a gas inducer, for example, which draws oifthe furnace gases andforces them through the usual cleaning apparatus ofagaswor Inthiscasethe samegas feeding machine can also naturally be used in order to forcethe gas also through the converter plant and the remaining apparatusconnected therewith. A uniform loading of all the apparatus serving forthe further treatment of the furnace gases is thereby attained withminimum expenditure of power. It is also desirable to add the oxygennecessary for the additional heating of the steam-gas mixture at theinitial contact on the low pressure side of the gas suction apparatus inorder to be able to carry out more satisfactorily with excess of oxygenin the purification of iron oxide the preliminary removal of hydrogensulphide from the gases` to be converted.

It should be noted that the method can be carried out also underpressures higher than 1 atmosphere where such a method appears moreeconomical in particular cases.

Example One mode of carrying my novel process into effect will now bedescribed by way of example and with reference to the accompanyingdrawing.

A carbon gas purified from hydrogen sulphide in known manner, forinstance, by means of an iron oxide purifying substance, not shown, andcontaining about 6.5 percent carbon monoxide and 0.4 percent oxygen isforced from the furnace house through the pipe line I and the compresser2 into the saturator 3 in order to be depoisened. In the saturator, thegas is rinsed wi-th hot water supplied from a scrubber I6, as indicatedat 4, and, if desired, by direct addition of steam through a pipe 5, soas to saturate it with steam to a dew point of about 65 to 75 C., Thegas leaving the saturator with a temperature of about 75 C. is directed,through a pipe 6, into .the heat exchanger 1 and preheated to about 320C., and then, through a pipe 8, into a contact furnace 9 having threecompartments I0, Il and I2. Provided in the topmost chamber I is acontact, preferably containing copper, and consisting, for instance, ofpumice stone on which about 10 percent cupric oxide are deposited,preferably on its surface.

In the compartments li and I2 there are provided contacts of a differentcomposition from the contact in chamber i0, preferably a contactcontaining chromium and iron, for instance, an iron-chromium contactconsisting of 96 to 98 percent of iron oxide and 2 to 4 percent ofchromium oxide. The gas and steam mixture, preheated to 320 C., at firstpasses through the contact of chamber I0, being preheated to about 370C. owing to the oxidation which is favoured at this contact. Followingthis the gas and steam vmixture which is extensively freed from oxygenpasses through the contact chambers Il and I2 in which the steamreaction is taking place. Since the temperature of the gas and steammixture after passage through the contact Il rises to about 420 C., itis desirable toreduce the temperature of the reaction mixture before itenters into the chamber I2, by adding non-superheated steam or condensedwater through a pipe line I3, so that the gas leaving this chamber hasa. temperature of about 380 C. The gas and steam mixture leaves thecontact furnace at its lower end and is directed through'the pipe I4into the heat exchanger I for heating the steam-saturated carbon gases,and then the converted gas mixture having a temperature of about 110 C.is directed through the pipe line i5 into the scrubber I8 wherein it iscooled down by water supplied through a pipe I1. As mentioned above thewater discharged from the scrubber through pipe 4 is used for saturatingthe furnace gases coming from the compressor, while the converted gasdischarged through line I8 passes into a cooler i9 and is cooled thereinby water fed at 20. The cooled gas is then directed, through a pipe 2|,into a CO2-washer 22. The main quantity of the gas freed from CO2 thenis directed through a pipe 23 into a further cooler 24, cooled down tothe desired temperature by means of water fed through a pipe 25, anddischarged through a pipe 26.

The compressor 2 is adjusted in such a manner as to force through theplant a uniform quantity of gas corresponding to the maximum output ofgas supplied from the furnace house through the pipe line l. Now, if forany reason there is produced in the furnace house less than this maximumquantity of gas for which the condenser has been adjusted, thecompressor 2 automatically draws the balance from the carbon dioxidewasher 22, through the pipe line 21 and regulator 28 which permits thepassage of gas in the direction of arrow 29 only. In this manner it isachieved that a constant amount of gas is permanently circulatingthrough the Whole converter plant. Inasmuch as the content of carbonmonoxide in the furnace gas is approximately inversely proportional tothe quantity of gas produced in the furnace house, it is also achievedthat a gas mixture is forced through the converter plant having asubstantially constant CO content which in the present case amounts to iabout 6.5 percent.

The method of the present invention has been described in detail withreference to specific embodiments. It is to be understood, however, thatthe invention is not limited by such specific reference but is broaderin scope and capable of other embodiments than those specificallydescribed.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention, which, as amatter of language, might f be said to fall therebetween.

This is a continuation in part of my co-pending patent application Ser,No. 216,348, led June 28, 1938, entitled: Method for the removal ofcarbonic oxide from gases or mixtures of gases containing organicsulphur compounds, etc.

I claim:

1. In a method for the removal of carbon oxide by means of steamcatalysis from gases which include coal distillation products" and whichcontain oxygen and organic sulphur compounds and which fluctuate inquantity and in CO content, which method comprises conversion of theoxygen content at a preliminary contact of different composition fromthe main contacts used for the hydrogen catalysis, the steps ofwithdrawing a portion from the main stream subjected to steam catalysisfollowing said steam catalysis and adding said withdrawn portion to theinitial gases, as the quantity of gas delivered from the furnace fallsbelow the maximum with consequent increase of the carbon oxide content,the quantity of gases thus added being such as to maintain asubstantially constant quantity and composition of the gas to besubjected to the catalysis.

2. In a method for the removal of carbon oxide by means of steamcatalysis from gases which include coal distillation products and whichcontain oxygen and organic sulphur compounds and which fluctuate inquantity andin C0 content, which method comprises conversion oi' theoxygen content at a preliminary contact oi' diiferent composition fromthe main contacts used for the hydrogen catalysis, the steps ofwithdrawing a. portion from the main stream subjected to steam catalysisfollowing said steam catalysis freeing said portion from carbonio acid,and add ing said withdrawn portion to the initial gases, as the quantityof gas delivered from .the furnace falls below the maximum withconsequent increase of the carbon oxide content, the quantity of gasesthus added being such as to maintain a substantially constant quantityand composition of the gas to be subjected to the catalysis.

3. In a method for the removal of carbon oxide by means of steamcatalysis from gases which include coal distillation products and whichoontain oxygen and organic sulphur compounds and which fluctuate inquantity and in CO content. which method comprises elimination of theorganic sulphur compounds and subsequent conversion of the oxygencontent at a preliminary contact of different composition from the maincontacts used for the hydrogen catalysis, the steps of withdrawing aportion from the main stream subjected to steam catalysis following saidsteam catalysis and adding said withdrawn portion to the initial gases,prior to purification of the latter from organic sulphur compounds, asthe quantity of gas delivered from the furnace falls below the maximumwith consequent increase of the carbon oxide content, the quantity ofgases thus added being such as to maintain a substantially constantquantity and composition of the gas to be subjected to the catalysis.

RICHARD BRANDT.

